In this case it is more fuel efficient to stay in gear because you are letting gravity run the engine instead of fuel. In addition, it saves wear on your brakes because the partial-vacuum created in the engine leads to engine-braking. In many states in the US it is actually required that you stay in gear when going downhill so that you have better control over the vehicle.
“Coasting only happens when you are going downhill.”
To quote the Wikipedia article on energy-efficient driving :. Coasting with a vehicle not in gear is prohibited by law in most US states. The answer depends a great deal on the control system around the engine, and how fast you are going down the hill relative to the gear you are in.
For a basic engine system, like s or earlier, at idle throttle setting the fuel usage would go up a bit with engine speed. The higher engine speed would make a higher vacuum, which would pull in more fuel-air mixture.
- “Coasting only happens when you are going downhill.”!
- Recommended Services.
- Under the Hood: Coasting in gear more fuel-efficient than coasting in neutral?
- Watch Next?
- I CAN DO ALL THINGS Child of God?
If the downhill speed and gearing come out to the same engine speed as idle, then the fuel usage would be the same as idle. If you used a higher gear so that the engine would go slower, then it might use a little less fuel. However, there isn't a lot of engine speed room below idle. You run the risk of the engine bucking, which is not a good idea to subject the power train to. To meet late s pollution limits, some cars were equipped with a "decel valve".
Coasting Downhill – The Church at Shelby Crossings
This sort of effectively stepped on the gas for you when the engine was undergoing rapid deceleration, or was externally driven rapid deceleration is being "externally" driven from the momentum of the engine. The reason was that this condition with low fuel input would cause more pollutants to be emitted. The short term expedient was to give it more fuel.
In such a case, running the engine faster than idle due to coasting down a hill in a sufficiently low gear would definitely use more fuel than idling in neutral down the hill. With more modern control systems, it's hard to know. Some cars detect this condition and effectively shut down the engine. No excess or call out charges. We reach 4 out of 5 customers within an hour. What is coasting and why is it bad?
Thursday, 18 July , What is coasting? Green Flag greenflag.
So remember: Avoid coasting
The AA theaa. RAC rac. All competitor prices have been based on our most popular 3 star level of cover for a vehicle aged up to 5 years old. Cover includes nationwide recovery, home assistance, alternative transport, overnight accommodation and key assist. Maybe I'll squeeze in a round of golf or a short vacation, but that's as far as I let myself go.
It's easier to stay motivated than to get motivated again. An elderly carpenter was ready to retire. He told his employer of his plans to leave the house-building business and live a more leisurely life so he and his wife could enjoy their extended family.
If You're Coasting: You're Going Downhill
He would miss the paycheck, but he needed to retire. They could get by. The contractor was sorry to see his good worker go and asked if he would build just one more house as a personal favor. The carpenter said yes, but in time it was easy to see that his heart was not in his work. He resorted to shoddy workmanship and used inferior materials.
It was an unfortunate way to end a dedicated career.
When the carpenter finished his work his employer came to inspect the house. He asked, "Are you satisfied with the house? The carpenter was shocked! What a shame! If he had only known he was building his own house, he would have made sure it was first class. So it is with us.